Re: exfat upcase table for code points above U+FFFF (Was: Re: [PATCH] staging: exfat: add exfat filesystem code to staging)

[Sasha Levin]

On Tue, Apr 21, 2020 at 11:30:45PM +0200, Pali Rohár wrote:
> On Thursday 13 February 2020 16:18:47 Sasha Levin wrote:
> > On Thu, Feb 13, 2020 at 01:06:56AM +0100, Pali Rohár wrote:
> > > In released exFAT specification is not written how are Unicode code
> > > points above U+FFFF represented in exFAT upcase table. Normally in
> > > UTF-16 are Unicode code points above U+FFFF represented by surrogate
> > > pairs but compression format of exFAT upcase table is not clear how to
> > > do it there.
> > >
> > > Are you able to send question about this problem to relevant MS people?
> > >
> > > New Linux implementation of exfat which is waiting on mailing list just
> > > do not support Unicode code points above U+FFFF in exFAT upcase table.
> >
> > Sure, I'll forward this question on. I'll see if I can get someone from
> > their team who could be available to answer questions such as these in
> > the future - Microsoft is interested in maintaining compatiblity between
> > Linux and Windows exFAT implementations.
>
> Hello Sasha! Have you got any answer from exfat MS team about upcase
> table for Unicode code points above U+FFFF?

Sorry for taking so long. This is my understanding from the Windows
folks: Windows filesystems just don't support variable encoding length,
and expect UCS-2 strings.

--
Thanks,
Sasha